Carrier 38AUZ appendix Compressor Protection, Lubrication

Table 7 — CADM Troubleshooting

Miswired Module Indication	Recommended Troubleshooting Action
Green LED is not on,	Determine if both R and C module terminals are
module does not power up	connected. Verify voltage in present at module’s R and C
	terminals.
	NOTE: The CADM requires a constant nominal 24VAC
	power supply. The wiring to the module’s R and C
	terminals must be directly from the control transformer.
	The module cannot receive its power from another device
	that will interrupt the 24VAC power supply. See Fig. 20,
	the 38AU Wiring Diagram.
Green LED Intermittent,	Determine if R and Y terminals are wired in reverse. Verify
module powers up only	module’s R and C terminals have a constant source. See
when compressor runs	“NOTE” above for details on R and C wiring.
TRIP LED is on but system	Verify Y terminal is wired properly per the 38AU wiring
and compressor check OK	diagram (see Fig. 19). Verify voltage at contactor coil falls
	below 0.5VAC when off. Verify 24VAQC is present across
	Y and C when thermostat demand signal is present. If not,
	R and C are reverse wired.
TRIP LED and ALERT LED	Verify R and C terminals are supplied with 19-28VAC.
flashing together
ALERT Flash Code 3	Verify Y terminal is connected to 24VAC at contactor coil.
(Compressor Short Cycling)	Verify voltage at contactor coil falls below 0.5VAC when
displayed incorrectly	off.
ALERT Flash Code 5 or 6	Check that compressor T1 and T3 wires are through
(Open Circuit, Missing Phase)	module’s current sensing holes. Verify Y terminal is
displayed incorrectly	connected to 24VAC at contactor coil. Verify voltage at
	contactor coil falls below 0.5VAC when off.
Alert Flash Code *	Determine if module’s Y terminal is connected. Verify Y
(Welded Contactor)	terminal is connected to 24VAC at contactor coil. Verify
displayed incorrectly	24VAC is present across Y and C when thermostat
	demand signal is present. If not, R and C are reverse
	wired. Verify voltage at contactor coil falls below 0.5VAC
	when off.

Crankcase Heater — The heater prevents refrigerant migration and compressor oil dilution during shutdown when- ever compressor is not operating. The heater is wired to cycle with the compressor; the heater is off when compressor is run- ning, and on when compressor is off.

The crankcase heater will operate as long as the power circuit is energized.

Compressor Protection

COMPRESSOR OVERTEMPERATURE PROTECTION (IP) — A thermostat installed on the compressor motor wind- ing reacts to excessively high winding temperatures and shuts off the compressor.

CRANKCASE HEATER — The heater minimizes absorp- tion of liquid refrigerant by oil in the crankcase during brief or extended shutdown periods. The main disconnect must be on to energize the crankcase heater.

IMPORTANT: Never open any switch or disconnect that energizes the crankcase heater unless unit is being serviced or is to be shut down for a prolonged period. After a pro- longed shutdown on a service job, energize the crankcase heater for 24 hours before starting the compressor.

ADVANCED SCROLL TEMPERATURE PROTECTION (ASTP) — See “Advanced Scroll Temperature Protection (ASTP)” on page 15.

Low-Pressure Switch — The 38AUZ low-pressure switch is stem-mounted on the suction line. Switches are all fixed, non-adjustable type.

High-Pressure Switch — The 38AUZ high-pres- sure switch is stem-mounted on the discharge line. The switch is a fixed, non-adjustable type.

Outdoor Fans — Each fan is supported by a formed-wire mount bolted to the fan deck and covered with a wire guard. Fan motors have permanently lubricated bearings.

Lubrication

FAN MOTORS have sealed bearings. No provisions are made for lubrication.

COMPRESSOR has its own oil supply. Loss of oil due to a leak in the system should be the only reason for adding oil after the system has been in operation.

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